1. Field of the Invention
The present invention generally relates to optical absorption spectroscopy and, more particularly, to a method and apparatus for performing scanning tunneling optical absorption spectroscopy. Optical absorption and modulated optical absorption spectra can be measured with spatial resolutions below the wavelength of the probing light using a scanning tunneling optical absorption spectroscopy according to the present invention.
2. Description of the Prior Art
Optical absorption spectra are obtained in conventional optical absorption spectroscopy by the passage of probing light from a light source through a selectively absorbing sample that is cooler than the light source. The spatial resolution of conventional optical absorption spectroscopy is limited to a wavelength of the probing light. Because of this limitation in spatial resolution, it has not been possible to use conventional optical absorption spectroscopy to optically probe individual features at the micron scale.